The common issues, most-likely-fix first. Stuck after trying these? Email hello@realmomentum.app with what you tried — a real person reads it.
Sync runs through your iCloud account, so the checklist is: both devices signed into the same Apple ID; iCloud enabled for Momentum (System Settings → your name → iCloud on Mac; Settings → your name → iCloud on iPhone); both devices online. Then give it a minute — CloudKit batches changes, and a just-edited task can take a moment to appear.
Still stuck: quit and relaunch the app on both devices (this nudges a fresh sync), and check that iCloud storage isn't full — a full quota fails silently, which is Apple's choice, not ours.
Almost always a shortcut collision: macOS reserves ⌃Space for input-source switching when more than one keyboard layout is enabled. Check System Settings → Keyboard → Keyboard Shortcuts → Input Sources — if "Select the previous input source" is bound to ⌃Space, disable it or rebind it. Spotlight-replacement apps (Raycast, Alfred) can also claim the combo; check their preferences if you run one.
Momentum needs calendar permission: System Settings → Privacy & Security → Calendars → enable Momentum (on iPhone: Settings → Privacy & Security → Calendars). If permission is granted and events are still missing, check which calendars are enabled in the app's settings — a work calendar that lives in a different account is the usual suspect.
Triage needs a network connection — the fallback analysis runs off-device. If you're using your own API key (BYOK), the two usual causes are a mistyped key and an Anthropic account with no credits; re-enter the key in Settings and check your balance at console.anthropic.com. If errors persist on the managed path, that's our side — email us, and meanwhile manual triage keeps working: same flow, your judgment instead of suggestions.
After an app update, widgets occasionally need re-adding: long-press the Home or Lock Screen → remove the Momentum widget → add it again. iOS also throttles widget refreshes to save battery, so a small delay after adding a task is normal, not broken.
Before assuming the worst: search for it with ⌘F — search covers everything, including Reference, Someday, and the Logbook. The usual explanations: it was completed (Logbook), triaged into a project you're not looking at, or parked in Someday. If it's genuinely gone, email us with the task title and roughly when you last saw it.